如何干净地结束CDI @ConversationScoped [英] How to cleanly end a CDI @ConversationScoped

问题描述

我的项目正在使用JSF2.0和CDI.对于一页，我希望我的支持bean与页面的寿命相匹配. @ViewScoped似乎很合适，但它不是CDI的一部分，因此使我们的解决方案不一致.然后，我的下一个选项将是CDI @ConversationScoped.在我看来，标记对话边界的唯一方法是通过对话.begin和conversation.end进行编程的方式(我使用了Seam 2.x，在那里可以使用注释来标记对话边界).我的页面位于具有全局导航的通用布局中，这意味着有无限"的方式可以离开我的页面.如何确定用户选择哪种对话方式都可以结束(例如，单击全局导航选项，而这完全不在我的支持Bean的控制范围之内)?我希望该解决方案不会将代码传播到其他模块.如果这是不可避免的，我希望可以以跨领域(AOP)的方式实施.

My Project is using JSF2.0 and CDI. For one page, I want my backing bean to match the lifespan of the page. @ViewScoped seems a perfect fit but it's not part of CDI and then make our solution not consistent. Then my next option would be the CDI @ConversationScoped. Seems to me the only way to mark the boundary of a conversation is the program way via conversation.begin and conversation.end (I have used Seam 2.x, there you can use annotations to mark conversation boundary). My page is sitting in a common layout with global navigation, which means there are "unlimited" ways to leave my page. How can I make sure the conversation is ended whichever way the user might choose (e.g. clicking on a global navi option which is totally outside of my backing bean's control)? And I hope the solution would not spread the code to other modules; and if that's inevitable, I hope it could be implemented in a cross-cutting manner (AOP).

推荐答案

这可以通过自定义ConfigurableNavigationHandler来实现.

This can be achieved with a custom ConfigurableNavigationHandler.

1. 实现JSF NavigationHandler

1. Implement a JSF NavigationHandler

 public class NavigationHandlerTest extends ConfigurableNavigationHandler {

 private NavigationHandlerTest concreteHandler;

 public NavigationHandlerTest(NavigationHandler concreteHandler) {
      this.concreteHandler = concreteHandler;
 }


 @Override
 public void handleNavigation(FacesContext context, String fromAction, String outcome) 
 {
    //here, check where navigation is coming from and based on that, retrieve the CDI bean and kill the conversation
     if(fromAction.equals("someAction"){
     BeanManager theBeanManager = getBeanManager(context);
     Bean bean = theBeanManager.getBeans("yourCDIBean").iterator().next() 
     CreationalContext ctx = theBeanManager.createCreationalContext(bean);
     MyBeanType o = theBeanManager.getReference(bean, bean.getClass(), ctx); //retrieve the bean from the manager by name. You're guaranteed to retrieve only one of the same name;
     o.getConversation.end(); //end the conversation from the bean reference
      }

     //proceed with normal navigation
     concreteHandler.handleNavigation(context, fromAction, outcome);   

 }

 //This method provides access to the cdi bean manager. You need it to be able to 
 //gain access to the cdi bean and from that to the injected conversation instance
 public BeanManager getBeanManager(FacesContext facesContext){
   BeanManager cdiBeanManager = (BeanManager)((ServletContext) facesContext.getExternalContext().getContext()).getAttribute("javax.enterprise.inject.spi.BeanManager"); 
    return cdiBeanManager;
 }


   } 

在 faces-config.xml

 <application>
     <navigation-handler>com.foo.bar.NavigationHandlerTest</navigation-handler>
 </application>

这种方法是集中式且微创的

This approach is centralized and minimally invasive

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